On Sat, 18 Jun 2011 17:43:16 -0700, Eric Anholt <e...@anholt.net> wrote: > Fixes oglconform failure about our ARB_texture_float GetTexImage. > Note that clamping does not appear in the "Conversion to L" stage of > the GL 3.2 spec, and the next stage of "Final conversion" does > clamping according to CLAMP_READ_COLOR. > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=36892
So, on further thought (after trying to build testcases), I'm not sure
what the correct answer is here. Here's a bit I had in the test I was
writing:
+/** @file spec/arb_color_buffer_float/getteximage.c
+ *
+ * Tests that read color clamping affects glGetTexImage as
+ * specified by ARB_color_buffer_float.
+ *
+ * From page 373 of the GL 3.2 compatibility spec ("Texture Queries"):
+ *
+ * "No pixel transfer operations are performed on this image, but
+ * pixel storage modes that are applicable to ReadPixels are
+ * applied."
+ *
+ * From page 313 of the GL 3.2 compatibility spec ("Final Conversion"):
+ *
+ * "Read color clamping is controlled by calling ClampColor (see
+ * section 3.7.5) with target set to CLAMP_READ_COLOR. If clamp
+ * is TRUE, read color clamping is enabled; if clamp is FALSE,
+ * read color clamping is disabled. If clamp is FIXED_ONLY, read
+ * color clamping is enabled if the selected read color buffer
+ * has fixed-point components."
+ *
+ * This step of ReadPixels is part of the "pixel storage modes" block
+ * in the diagram on page 309. However, it doesn't make a lot of
+ * sense for reading of texture components to be clamped according to
+ * whether the color buffer has fixed-point components. Let's
+ * interpret this as meaning clamping according to whether the texture
+ * storage has fixed-point components. Also, the interpretation of
+ * read clamping applying to GetTexImage results means that before
+ * ARB_color_buffer_float, there was no way to GetTexImage the
+ * negative components of a snorm texture, which seems odd.
+ */
Anyone have any guidance here?
pgpmtG64IMMIX.pgp
Description: PGP signature
_______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
